Quick Check --- This trailer hitch socket has one side to connect the 7-pin plug of a trailer and another side to connect the 7-pin plug of a vehicle. This tester quickly indicates whether a fault is in vehicle wiring or trailer wiring, which can effectively test the problem of 7-pin plug and socket connection.European Universal Standard --- Passes European CE and ROHS certification, ensuring maximum strength and durability for long-lasting use. This trailer tester is a handy tool you will need.Reliable Quality --- The 7-pin trailer tester offers safe and reliable performance with a practical design. It has a user-friendly appearance and is convenient to use. The trailer tester socket is widely suitable for caravans, RVs, vehicles, trucks, and trailers. Testing requires a 9V battery (not included).High Performance --- The automotive trailer socket tester is made of high-quality ABS and copper material, with a frosted surface for durability and reliability. It ensures resistance and long-lasting performance. One side connects to a 7-pin plug and the other to a 7-pin socket. It can also be used with a 13-pin adapter.